The present invention relates to a rotary vane-type refrigerant compressor which is adapted for use in an air refrigeration system. More specifically, it relates to an arrangement in the rotary compressor for damping a pulsating flow of refrigerant gas occurring during the operation of the compressor.
There is known a typical rotary compressor of the above type which has a rotor carried by a drive shaft and disposed in an elliptical chamber of a cylinder block which is enclosed by a housing and whose axial ends are closed by front and rear side plates. The rotor has a plurality of approximately radial slots in which their associated vanes are slidably received such that their outer ends are brought in fluid-tight contact with the inner elliptical surface of the rotor chamber of the cylinder block under the influence of centrifugal force developed by rotation of the rotor and such that a plurality of compression chambers are formed, each defined by two adjacent vanes, the outer peripheral surface of the rotor, the inner elliptical surface of the cylinder block and the inner surfaces of the front and rear side plates. As the rotor is rotated in the rotor chamber, the volume of each compression chamber is increased and decreased alternately so as to draw a refrigerant gas into the compression chamber and then compress and discharge the gas into a discharge chamber which is formed between the cylinder block and the housing.
Between the rear side plate and the rear portion of the housing is formed a compartment accommodating therein an oil separator which is in communication with the discharge chamber through a compressed gas passage and having at its bottom an oil reservoir where lubricating oil contained in the refrigerant gas and separated therefrom by the oil separator is received. Therefore, the space in the oil separator compartment above the level of the reservoir of oil is filled with refrigerant gas under a discharge pressure. In operation of the compressor, the lubricating oil reserved in the reservoir at the bottom of the oil separator compartment is subjected to the relatively high pressure of the refrigerant gas in the space thereabove, which forces part of the oil to flow through an oil passage formed in the rear side plate for feeding to various parts of the compressor which need be lubricated, such as bearings supporting the drive shaft, sliding surfaces between the rotor and the front and rear side plates, and the vane slots in which the vanes slide.
Since discharging of refrigerant gas from the respective compression chambers into the discharge chamber takes place intermittently, the gas pressure in the discharge chamber is varied accordingly, thereby causing a pulsating stream of gas which, if discharged from the compressor without being damped, causes harmful vibration and hence noise development in component parts of the air conditioning system in which the compressor is incorporated. The upper space in the oil separator compartment where the compressed refrigerant gas prevails can serve to allow the compressed refrigerant of the pulsating stream to be expanded therein, thus damping or diminishing the pulsation of the refrigerant.
During operation of the compressor at a low speed, however, the flow of the compressed refrigerant gas passing from the discharge chamber into the oil separator compartment is reduced, so that more lubricating oil tends to be separated from the refrigerant and, therefore, the level of the lubricating oil in the reservoir is raised and hence the pulsation-damping space above the oil level is reduced. Consequently, the effect of the space to damp the pulsation is weakened, with the result that vibration and noise development may be increased during operation of the compressor at a low speed.